Discipline and Laughter

I have always thought of myself as kind of a hard nose when it comes to discipline, especially before I had my own child. I am still more of a disciplinarian than Ryan is, but he's getting better. It used to make me so mad when he would be trying to discipline Adriana and then laugh or when I was getting on to her and he would laugh. How are they suppose to take you seriously if you're laughing? Well last night I was asking/telling her to pick up her books. After a while it was more of the fact of the matter than actually cleaning them up. Ryan thinks I should just give in if she doesn't want to clean up. That idea doesn't fly with me. Anyway, last night me and Ryan were getting on to her and she just kept saying "no" and smiling in defiance. I just was stretched to my max and for some reason, I started to smile. I couldn't help it, the look she was giving me was cracking me up. Of course Ryan sees me starting to smile and busts up laughing and then it makes me start to laugh. We tried to conceal our laughing and still try to get on to her to clean up her books, but she shot me another look and we busted up again. Its like when you know you're not suppose to laugh it makes you want to laugh even more. We finally got the books cleaned up and all was right with the world. I just get frustrated when she makes me laugh when I'm trying to discipline because I just feel like she won't take me seriously if I'm laughing at her bad behavior.